Nearly 13 million US Facebook users do not use, or are not aware of, the site’s privacy controls, according to a Consumer Reports investigation on Facebook and privacy. As a result, users are potentially exposing personal information beyond their network of Facebook friends.

The report also revealed that a projected 4.8 million people have posted about where they planned to go on a certain day, a potential tip-off to burglars, while 4.7 million have “liked” a Facebook page about health conditions or treatments, details that insurers might use against them.

That’s 13 out of 150 million US users, or roughly 8.5%. Considering that Mark (DataSuckah) Zuckerberg strip-mines data under even the tightest privacy controls, it’s hard to imagine how far he gets with people who don’t have any.

(Full disclosure: The hardworking staff has chosen no privacy settings, mostly because we’ve chosen not to share anything of value on Facebook.)

But for all your hyperactive Facebooknauts, forewarned is forearmed.

P.S. The Consumer Reports link above includes plenty of practical advice for protecting your data, as much as is possible on Facebook.